.\" -*- nroff -*-
.\" Copyright 2010 Cisco Systems, Inc.  All rights reserved.
.\" Copyright 2006-2008 Sun Microsystems, Inc.
.\" Copyright (c) 1996 Thinking Machines Corporation
.\" $COPYRIGHT$
.TH MPI_Type_commit 3 "Jun 10, 2020" "4.0.4" "Open MPI"
.SH NAME
\fBMPI_Type_commit\fP \- Commits a data type.

.SH SYNTAX
.ft R
.SH C Syntax
.nf
#include <mpi.h>
int MPI_Type_commit(MPI_Datatype *\fIdatatype\fP)

.fi
.SH INPUT PARAMETER
.ft R
.TP 1i
datatype
Data type (handle).

.SH OUTPUT PARAMETER
.ft R
.TP 1i
IERROR
Fortran only: Error status (integer).

.SH DESCRIPTION
.ft R
The commit operation commits the data type. A data type is the formal description of a communication buffer, not the content of that buffer. After a data type has been committed, it can be repeatedly reused to communicate the changing content of a buffer or, indeed, the content of different buffers, with different starting addresses.
.sp
\fBExample:\fP The following Fortran code fragment gives examples of using MPI_Type_commit.
.sp
.nf
    INTEGER type1, type2
    CALL MPI_TYPE_CONTIGUOUS(5, MPI_REAL, type1, ierr)
                  ! new type object created
    CALL MPI_TYPE_COMMIT(type1, ierr)
                  ! now type1 can be used for communication
.fi
.sp
If the data type specified in \fIdatatype\fP is already committed, it is equivalent to a no-op.

.SH ERRORS
Almost all MPI routines return an error value; C routines as the value of the function and Fortran routines in the last argument. C++ functions do not return errors. If the default error handler is set to MPI::ERRORS_THROW_EXCEPTIONS, then on error the C++ exception mechanism will be used to throw an MPI::Exception object.
.sp
Before the error value is returned, the current MPI error handler is
called. By default, this error handler aborts the MPI job, except for I/O function errors. The error handler may be changed with MPI_Comm_set_errhandler; the predefined error handler MPI_ERRORS_RETURN may be used to cause error values to be returned. Note that MPI does not guarantee that an MPI program can continue past an error.

